Coal binder composition

ABSTRACT

The presently claimed invention relates to a briquette comprising coal fines and a binder composition comprising at least one homo- or copolymer of (meth)acrylic acid (i) and at least one alkyl(meth)acrylate-styrene-copolymer (ii), a method for manufacturing said briquette and the use of a binder composition for the agglomeration of coal fines.

The presently claimed invention relates to a briquette comprising coalfines and a binder composition comprising at least one homo- orcopolymer of (meth)acrylic acid (i) and at least onealkyl(meth)acrylate-styrene-copolymer (ii), a method for manufacturingsaid briquette and the use of a binder composition for the agglomerationof coal fines.

During coal mining coal fines are obtained in addition to lumps of coal.Further processing of said coal fines is possible, e.g. by usingfloatation processes. The thus obtained coal fines concentrate isbriquetted and the obtained tailings which still contain a considerableamount of coal fines are discarded onto a mining waste tip. However, insome regions, e.g. South Africa, usually the whole coal fines fractionis dumped onto a mining waste heap without any further processing. Sucha coal fines may comprise more than 20 wt.-% of unburnable mineralsrendering the coal fines as such inopportune to use as fuel.

Large amounts of coal fines on mining waste tips lead to significantamounts of escaping coal dust which is undesirable and maybe in thefuture or already is prohibited by law in some countries. In somecountries even existing mining waste heap have to be closed and the coalfines removed. Although direct combustion of coal fines having high ashcontent is not possible, such coal fines can be combusted in a plantprovided that the coal fines are present as briquettes. Moreover,briquettes of course are much easier to transport compared to coalfines. Thus by using briquettes the combustion can take place whereneeded. However, for this purpose the briquettes need to be stableduring transport and in particular resistant to damage by dropping froma certain height as transport from one vessel to another frequentlyoccurs, e.g. when the pellets are moved from a train to a ship or thelike. In case the briquettes break during transport or the surface isabraded due to friction undesired small particles are formed and evencoal fines may be formed causing environmental contamination and, incase the worst comes to the worst, even dust explosions.

For briquette formation of most coal fines usually a polyvinyl alcohol(PVA) binder is added as a diluted solution that requires heating thePVA to a temperature of >80° C. for solubilization, which is undesirablefrom an economic point of view. Moreover, the mechanical stability ofsuch PVA-containing briquettes still needs improvement.

Thus, the object of the presently claimed invention is to providebriquettes comprising coal fines and a binder composition which show agood mechanical stability and strength, whereby the mechanical stabilityand strength is developed at relatively low temperatures without theneed to heat the binder composition.

The object is achieved by providing briquettes that comprise coal finesand a binder composition comprising at least one homo- or copolymer of(meth)acrylic acid (i) and at least onealkyl(meth)acrylate-styrene-copolymer (ii).

Thus, in one embodiment, the presently claimed invention is directed toa briquette comprising

A) coal fines and

B) a binder composition comprising

-   -   (i) at least one homo- or copolymer of (meth)acrylic acid and    -   (ii) at least one alkyl(meth)acrylate-styrene-copolymer.

Preferably the presently claimed invention is directed to a briquettecomprising

A) coal fines and

B) a binder composition comprising

-   -   (i) at least one homo- or copolymer of (meth)acrylic acid, which        is not an alkyl(meth)acrylate-styrene-copolymer and    -   (ii) at least one alkyl(meth)acrylate-styrene-copolymer.

In the sense of the presently claimed invention the term “briquette”denotes a compressed block of any shape including spheres, rectangles,squares, rods, broken strips and broken sheets.

In the sense of the presently claimed invention the term “coal fines”denotes the entirety of solid inorganic components comprising coalparticles and ash particles. In the sense of the presently claimedinvention the term “coal particles” denotes particles consistingsubstantially, i.e. >85 wt.-%, of carbon. The term “ash particles”denotes particles of non-coal minerals including silica, clay andpyrite.

Usually the coal particles make up at least 50 wt.-%, more preferably atleast 60 wt.-% and most preferably at least 70 wt.-%, based on the totalweight of the coal fines.

The coal fines may further comprise ash particles. Although a low ashparticle content, e.g. 10 wt.-% or less, preferably 5 wt.-% or less,based on the total weight of the coal fines is preferable, the coalfines may comprise up to 40 wt.-% of ash particles determined accordingto standard gravimetric methods. The inventive pellets can still beutilized in a power plant, a coal liquefaction (Fischer-Tropsch/Sasolprocess) plant at such a high ash particle content. Preferably, the ashparticle content is up to 25 wt.-%, based on the total weight of thecoal fines. Coal fines with high ash particle content include wastecoal, run-of-mine coal and freshly mined coal.

Preferably, the coal fines comprise at least 50 wt.-% coal particleshaving a particle diameter of less than 1 mm determined according to DIN66165, more preferably comprise at least 75 wt.-% coal particles havinga particle diameter of less than 1 mm and most preferably consist ofcoal particles having a particle diameter of less than 1 mm.

In a preferred embodiment the coal fines comprise at least 50 wt.-% coalparticles having a particle diameter of less than 500 μm determinedaccording to DIN 66165, more preferably comprise at least 75 wt.-% coalparticles having a particle diameter of less than 500 μm and mostpreferably consist of coal particles having a particle diameter of lessthan 500 μm. In an especially preferred embodiment the coal finescomprise at least 50 wt.-% coal particles having a particle diameter ofless than 300 μm determined according to DIN 66165, more preferablycomprise at least 75 wt.-% coal particles having a particle diameter ofless than 300 μm and most preferably consist of coal particles having aparticle diameter of less than 300 μm.

Preferably, the coal fines comprise at least 50 wt.-% particles passingTyler Mesh 16 sieve (1 mm sieve opening), more preferably comprise atleast 75 wt.-% particles passing Tyler Mesh 16 sieve (1 mm sieveopening) and most preferably consist of particles passing Tyler Mesh 16sieve (1 mm sieve opening). Preferably, the coal fines comprise at least50 wt.-% particles passing Tyler Mesh 32 sieve (500 μm sieve opening),more preferably comprise at least 75 wt.-% particles passing Tyler Mesh32 sieve (500 μm sieve opening) and most preferably consist of particlespassing Tyler Mesh 32 sieve (500 μm sieve opening). Preferably, the coalfines comprise at least 50 wt.-% particles passing Tyler Mesh 48 sieve(300 μm sieve opening), more preferably comprise at least 75 wt.-%particles passing Tyler Mesh 48 sieve (300 μm sieve opening) and mostpreferably consist of particles passing Tyler Mesh 48 sieve (300 μmsieve opening).

Preferably the at least one homo- or copolymer of (meth)acrylic acid (i)is not an alkyl(meth)acrylate-styrene-copolymer (ii).

Preferably the at least one homo- or copolymer of (meth)acrylic acid (i)is selected from the group consisting of homopolymers of acrylic acid,optionally in form of its alkali metal salts, alkaline metal salts andammonium salts;

homopolymers of methacrylic acid, optionally in form of its alkali metalsalts, alkaline metal salts and ammonium salts;

copolymers of acrylic acid, optionally in form of its alkali metalsalts, alkaline metal salts and ammonium salts, and at least onenonionic monomer; and

copolymers of methacrylic acid, optionally in form of its alkali metalsalts, alkaline metal salts and ammonium salts, and at least onenonionic monomer.

In the sense of the presently claimed invention the at least one“nonionic monomer” is a monomer which is electrically neutral.Preferably nonionic monomers are selected from the group consisting ofmethacrylate, ethyl acrylate, propyl acrylate, butyl acrylate,acrylamide, methacrylamide, N-methylacrylamide, N-isopropylacrylamide,N-tert-butyl acrylamide, N-methylolacrylamide, N,N-dimethyl(meth)acrylamide, N-isopropyl(meth)acrylamide,N-(2-hydroxypropyl)methacrylamide, N-methylolacrylamide,N-vinyfformamide, N-vinylacetamide, N-vinyl-N-methylacetamide,poly(ethylene glycol)(meth)acrylate, poly(ethylene glycol) monomethylether mono(meth)acrylate, N-vinyl-2-pyrrolidone, glycerolmono((meth)acrylate), 2-hydroxyethyl(meth)acrylate, vinyl methylsulfoneand vinyl acetate. More preferably nonionic monomers are selected fromthe group consisting of acrylamide, methacrylamide,N-isopropylacrylamide, N-tert-butyl acrylamide, N-methylolacrylamide,methacrylate, ethyl acrylate, propyl acrylate and butyl acrylate.

More preferably the homo- or copolymers of (meth)acrylic acid (i) areselected from the group consisting of homopolymers of acrylic acid,optionally in form of its alkali metal salts, alkaline metal salts andammonium salts;

homopolymers of methacrylic acid, optionally in form of its alkali metalsalts, alkaline metal salts and ammonium salts;

copolymers of acrylic acid, optionally in form of its alkali metalsalts, alkaline metal salts and ammonium salts, and at least onenonionic monomer selected from the group consisting of acrylamide,methacrylamide, N-isopropylacrylamide, N-tert-butyl acrylamide,N-methylolacrylamide, methacrylate, ethyl acrylate, propyl acrylate andbutyl acrylate; and

copolymers of methacrylic acid, optionally in form of its alkali metalsalts, alkaline metal salts and ammonium salts, and at least onenonionic monomer selected from the group consisting of acrylamide,methacrylamide, N-isopropylacrylamide, N-tert-butyl acrylamide,N-methylolacrylamide, methacrylate, ethyl acrylate, propyl acrylate andbutyl acrylate.

Even more preferably the homo- or copolymers of (meth)acrylic acid (i)are selected from the group consisting of homopolymers of acrylic acid,optionally in form of its alkali metal salts, alkaline metal salts andammonium salts;

homopolymers of methacrylic acid, optionally in form of its alkali metalsalts, alkaline metal salts and ammonium salts;

copolymers of acrylic acid, optionally in form of its alkali metalsalts, alkaline metal salts and ammonium salts, and acrylamide; andcopolymers of methacrylic acid, optionally in form of its alkali metalsalts, alkaline metal salts and ammonium salts, and acrylamide.

In particular the at least one homo- or copolymer of (meth)acrylic acid(i) is comprising a copolymer of acrylic acid and acrylamide. Preferablythe at least one homo- or copolymer of (meth)acrylic acid (i) consistsof a copolymer of acrylic acid and acrylamide. For example, a copolymerof acrylic acid and acrylamide is available as Alcotac® CB6 of BASF. Itis further preferred that the at least one homo- or copolymer of(meth)acrylic acid (i) is comprising for exampie a polymer of acrylicacid, in particular polyacrylic acid. Preferably the at least one homo-or copolymer of (meth)acrylic acid (i) consists of polyacrylic acid.

Preferably the at least one homo- or copolymer of (meth)acrylic acid (i)has a weight average molecular weight of ≥1 000 to ≤5 000 000 g/mol,more preferably in the range of ≥10 000 to ≤500 000 g/mol, determinedaccording analysis via gel permeation chromatography.

Preferably the at least one copolymer of (meth)acrylic acid (i) isderived from a mixture comprising ≥50 wt.-%, more preferably ≥70 wt.-%,even more preferably ≥80 wt.-%, most preferably ≥90 wt.-%, methacrylicacid and/or acrylic acid, each optionally in form of its alkali metalsalts, alkaline metal salts and ammonium salts. The remainder of thecopolymers of (meth)acrylic acid (i) is derived from at least at leastone nonionic monomer as defined above.

Preferably the at least one alkyl(meth)acrylate-styrene-copolymer (ii)is different to the at least one homo- or copolymer of (meth)acrylicacid (i).

Preferably the at least one alkyl(meth)acrylate-styrene-copolymer (ii)is derived from a mixture comprising

at least one monomer A selected from the group consisting of esters ofacrylic acid or methacrylic acid with n-propanol, isopropanol,n-butanol, isobutanol, sec-butanol, tert-butanol, pentanol, hexanol,2-ethylhexanol, octanol, decanol, dodecanol and stearyl alcohol

and at least one monomer B selected from the group consisting of styreneand-alpha-methyl-styrene.

Preferably the mixture comprises ≥20 to ≤90 wt.-%, more preferably ≥40to ≤80 wt.-%, most preferably ≥50 to ≤70 wt.-%, of at least one monomerA, based on the total weight of the mixture. Preferably the mixturecomprises ≥10 to ≤80 wt.-%, more preferably ≥20 to ≤60 wt.-%, mostpreferably ≥30 to ≤50 wt.-%, of at least one monomer B, based on thetotal weight of the mixture.

Preferably the at least one monomer A is selected from the groupconsisting of esters of acrylic acid or methacrylic acid withn-propanol, isopropanol, n-butanol, isobutanol, sec-butanol,tert-butanol, pentanol, hexanol, 2-ethylhexanol, octanol, decanol,dodecanol or stearyl alcohol or mixtures thereof, more preferably withn-butanol, isobutanol, sec-butanol, tert-butanol, pentanol, hexanol,2-ethylhexanol, octanol, decanol, dodecanol or stearyl alcohol ormixtures thereof and most preferably with n-butanol, isobutanol,sec-butanol or tert-butanol.

The at least one alkyl(meth)acrylate-styrene-copolymer (ii) may also bederived from a mixture comprising other monomers in an amount of up to10 wt.-%, preferably 5 wt.-% based on the total weight of the mixture.In case these other monomers are present, they are preferably selectedfrom vinyl formate, vinyl acetate, vinyl propionate, acrylonitrile,methacrylonitrile, acrylic acid, methacrylic acid, acrylamide,methacrylamide, vinyl chloride, vinylidene chloride, vinyl ethyl ether,ethylene, propylene, butadiene, isoprene, N-vinylpyrrolidone,vinylsulfonic acid and alkali metal salts thereof,acrylamidopropanesulfonic acid and alkali metal salts thereof,sulfonated styrene and alkali metal salts thereof, acrylic acid,methacrylic acid, maleic acid, fumaric acid, itaconic acid, N-alkyl- andN-hydroxyalkylamides of ethylenically unsaturated C₃-C₆-mono- ordicarboxylic acids, diesters of dihydric alcohols of ethylenicallyunsaturated C₃-C₆-mono- or dicarboxylic acids, the vinyl or allyl estersof ethylenically unsaturated C₃-C₆-mono- or dicarboxylic acids,N,N′-divinyl- or N,N′-diallylurea derivatives or divinylaromatics.

In case other monomers are present usually not more than two othermonomers are present, preferably, not more than one. Most preferably noother monomers are present.

The at least one alkyl(meth)acrylate-styrene-copolymer (ii) may also bepresent as a mixture of two or morealkyl(meth)acrylate-styrene-copolymers (ii) according to the invention.Usually not more than three alkyl(meth)acrylate-styrene-copolymers (ii)are present, preferably only one alkyl(meth)acrylate-styrene-copolymer(ii) is present.

In particular the at least one alkyl(meth)acrylate-styrene-copolymer(ii) is comprising a butyl acrylate-styrene copolymer. Preferably the atleast one alkyl(meth)acrylate-styrene-copolymer (ii) consists of a butylacrylate-styrene copolymer. For example, a butyl acrylate-styrenecopolymer is available as Acronal@ S 728 of BASF.

It is further preferred, that the at least onealkyl(meth)acrylate-styrene-copolymer (ii) is formulated in a ready touse formulation together with preferably the at least one homo- orcopolymer of (meth)acrylic acid (i) which is not analkyl(meth)acrylate-styrene-copolymer (ii). Preferably, the at least onealkyl(meth)acrylate-styrene-copolymer (ii) is comprising a butylacrylate-styrene copolymer which is formulated in a formulation which iscomprising for example a copolymer of acrylic acid and acrylamide as theat least one homo- or copolymer of (meth)acrylic acid (i). Furtherpreferred is that the at least one alkyl(meth)acrylate-styrene-copolymer(ii) is comprising a butyl acrylate-styrene copolymer which isformulated in a formulation which is comprising for example a polymer ofacrylic acid, in particular polyacrylic acid, as the at least one homo-or copolymer of (meth)acrylic acid (i). For example, a formulationcomprising butylacrylate styrene copolymer and a polymer of acrylic acidin water is available as Alcotac® CBF60 from BASF.

Preferably the at least one alkyl(meth)acrylate-styrene-copolymer (ii)has a weight average molecular weight of ≥1 000 to ≤2 000 000 g/mol,more preferably in the range of ≥1 000 to ≤1 000 000 g/mol, even morepreferably in the range of ≥1 000 to ≤500 000 g/mol, determinedaccording to gel permeation chromatography measurement.

Preferably the binder composition comprises at least one cross-linkingagent (iii) selected from the group consisting of polymers having atleast one functional group which is selected from the group comprisinghydroxy, primary, secondary and tertiary amine, epoxy and aldehyde andpolyvalent metal complexes.

The cross-linking can also be effected by the addition of alkali.

Preferably the polyvalent metal in the polyvalent metal complex isselected from the group consisting of calcium, magnesium, zinc, barium,aluminum, zirconium, nickel, iron, cadmium, strontium, bismuth,beryllium, cobalt, lead, copper and antimony. Preferably the ligand forforming the polyvalent metal complex is selected from the groupconsisting of carbonic acid ion, acetic acid ion, oxalic acid ion, malicacid ion, hydroxyacetic acid ion, tartaric acid ion, acrylic acid ion,lactic acid ion, formic acid ion, salicylic acid ion, benzoic acid ion,gluconic acid ion, glutamic acid ion, glycine, alanine, ammonia,morpholine, ethylene diamine, dimethylaminoethanol, diethylaminoethanol,monethanolamine, diethanolamine and triethanolamine.

The polymers having at least one functional group which is selected fromthe group comprising hydroxy, primary, secondary and tertiary amine,epoxy and aldehyde comprise, as a rule, the substances known to theperson skilled in the art, generally used for aminoplasts orphenol-formaldehyde resins and usually referred to as curing agents,such as ammonium sulfate or ammonium nitrate or inorganic or organicacids, for example sulfuric acid, formic acid, or acid-regeneratingsubstances, such as aluminum chloride, aluminum sulfate, in each case inthe customary, small amounts, for example in the range from 0.1% byweight to 10% by weight, based on the total amount of cross-linkingagent (iii).

Phenol-formaldehyde resins (also referred to as PF resins) are known tothe person skilled in the art, cf. for example Kunststoff-Handbuch, 2ndedition, Hanser 1988, volume 10 “Duroplaste”, pages 12 to 40.

In particular the binder composition further comprises at least onecross-linking agent (iii), whereas the cross-linking agent (iii)preferably is comprising a phenol formaldehyde resin. For example,phenol formaldehyde resins are available from BASF as Alcotac® CBX60 orfrom Resichem as Reslink® GTC 50.

Here, aminoplast resin is understood as meaning polycondensates ofcompounds having at least one carbamide group optionally partlysubstituted by organic radicals (the carbamide group is also referred toas carboxamide group) and an aldehyde, preferably formaldehyde.

All aminoplast resins known to the person skilled in the art, can beused as suitable aminoplast resin. Such resins and their preparation aredescribed, for example, in Ullmanns Enzyklopädie der technischen Chemie,4th newly revised and extended edition, Verlag Chemie, 1973, pages 403to 424 “Aminoplaste”, and Ullmann's Encyclopedia of IndustrialChemistry, Vol. A2, VCH Veriagsgesellschaft, 1985, pages 115 to 141“Amino Resins”, and in M. Dunky, P. Niemz, Holzwerkstoffe and Leime,Springer 2002, pages 251 to 259 (UF resins) and pages 303 to 313 (MUFand UF with a small amount of melamine).

Preferred aminoplast resins are polycondensates of compounds having atleast one carbamide group, also partly substituted by organic radicals,and formaldehyde.

Particularly preferred aminoplast resins are urea-formaldehyde resins(UF resins), melamine-formaldehyde resins (MF resins) ormelamine-containing urea-formaldehyde resins (MUF resins).

Very particularly preferred aminoplast resins are urea-formaldehyderesins, for example Kaurit® glue types from BASF SE.

Further very preferred aminoplast resins are polycondensates ofcompounds having at least one amino group, also partly substituted byorganic radicals, and aldehyde, in which the molar ratio of aldehyde toamino group optionally partly substituted by organic radicals is in therange from 0.3 to 1.0, preferably from 0.3 to 0.60, particularlypreferably from 0.3 to 0.45, very particularly preferably from 0.30 to0.40.

Further very preferred aminoplast resins are polycondensates ofcompounds having at least one amino group —NH₂ and formaldehyde, inwhich the molar ratio of formaldehyde to —NH₂ group is in the range from0.3 to 1.0, preferably from 0.3 to 0.60, particularly preferably from0.3 to 0.45, very particularly preferably from 0.30 to 0.40.

Further very preferred aminoplast resins are urea-formaldehyde resins(UF resins), melamine-formaldehyde resins (MF resins) ormelamine-containing urea-formaldehyde resins (MUF resins), in which themolar ratio of formaldehyde to —NH₂ group is in the range from 0.3 to1.0, preferably from 0.3 to 0.60, particularly preferably from 0.3 to0.45, very particularly preferably from 0.30 to 0.40.

Further very preferred aminoplast resins are urea-formaldehyde resins(UF resins) in which the molar ratio of formaldehyde to —NH₂ group is inthe range from 0.3 to 1.0, preferably from 0.3 to 0.60, particularlypreferably from 0.3 to 0.45, very particularly preferably from 0.30 to0.40.

Said aminoplast resins are usually used in liquid form, generallysuspended in a liquid suspending medium, preferably in aqueoussuspension, but can also be used as a solid.

The solids content of the aminoplast resin suspensions, preferablyaqueous suspension, is usually from 25 to 90% by weight, preferably from50 to 70% by weight.

The aminoplast resins are prepared by known processes (cf.abovementioned Ullmann literature “Aminoplaste” and “Amino Resins”, andabovementioned literature Dunky et al.) by reacting the compoundscontaining carbamide groups, preferably urea and/or melamine, with theadehydes, preferably formaldehyde, in the desired molar ratios ofcarbamide group to aldehyde, preferably in water as a solvent.

The desired molar ratio of aldehyde, preferably formaldehyde, to aminogroup optionally partly substituted by organic radicals can also beestablished by addition of monomers carrying —NH₂ groups toformaldehyde-richer prepared, preferably commercial, aminoplast resins.Monomers carrying NH₂ groups are preferably urea or melamine,particularly preferably urea.

The resin constituents of the cross-linking agent (iii) can be used bythemselves, i.e. for exampie aminoplast resin as the sole resinconstituent of the cross-linking agent (iii) or PF resin as the soleconstituent of the cross-linking agent (iii).

The resin constituents of the cross-linking agent (iii) can, however,also be used as a combination of two or more resin constituents of thecross-linking agent (iii).

The binder composition further comprises additives that have anadvantageous effect on the overall characteristics of the briquette orthe process for manufacturing briquettes. Suitable additives includedefoaming agents, water-repellent agents, surfactants and coalescingsolvents.

The defoaming agents that are suitable for the inventively used bindercomposition can be those commonly used in the art. In some non-limitingembodiments of the present invention, examples of defoaming agents thatare suitable for the inventively used binder composition include, butare not limited to, polyol defoamers, polyether defoamers, mineral oildefoamers, silicone defoamers, or mixtures thereof. In some non-limitingembodiments of the present invention, the defoamers can be used in anamount of ≥0.01 wt.-% to ≤1.0 wt.-%, based on the total weight of thebinder composition.

The surfactants that are suitable for the presently claimed inventioninclude, but are not limited to, anionic surfactants, nonionicsurfactants, cationic surfactants and combinations thereof.

Examples of anionic surfactants that are suitable for the presentlyclaimed invention include, but are not limited to: alkylsulfates,alkylsulfonates, alkylbenzenesulfonates, alkyl polyoxyethylene ethersulfates, alkylpolyoxyethylene-propylene ether sulfates, sodium fattyalcohol succinic acid mono ester sulfonates, disodium fatty alcoholpolyoxyethylene ether, sulfosuccinates, disodium fatty alcoholpolyoxyethylene-propylene ether sulfosuccinates, alkylpolyoxyethylenephosphates, alkylpolyoxyethylene-propylene phosphates, and alkali metalsalts and ammonium salts of fatty acids. Examples of nonionicsurfactants that are suitable for the presently claimed inventioninclude, but are not limited to: linear or branched alkyl alcoholpolyoxyethylene ethers, linear or branched alkyl alcoholpolyoxyethylene-propylene ethers, fatty acid polyoxyethylene monoesters,fatty acid polyoxyethylene-propylene monoesters. In some non-limitingembodiments of the present invention, the EO (ethylene oxide) numbers ofpolyoxyethylene section in nonionic surfactants determine the HLB valueof the nonionic surfactants, and the HLB value of the nonionicsurfactants is typically in the range of about 20 to 40.

The water-repellent agents that are suitable for the presently claimedinvention include, but are not limited to, sodium oleates ororganosilicon compounds such as alkoxysilanes.

The coalescing solvents that are suitable for the presently claimedinvention include, but are not limited to, ethylene glycol monobutylether, ethylene glycol monoethyl ether, diethylene glycol monomethylether, diethylene glycol monoethyl ether and diethylene glycol monobutylether.

Preferably, the binder composition comprises

-   ≥10 wt.-% to ≤70 wt.-% (i) at least one homo- or copolymer of    (meth)acrylic acid,-   ≥10 wt.-% to ≤70 wt.-% (ii) at least one    alkyl(meth)acrylate-styrene-copolymer,-   ≥0.1 wt.-% to ≤5 wt.-% (iii) at least one cross-linking agent,-   ≥20 wt.-% to ≤80 wt.-% water and-   ≥1 wt.-% to ≤80 wt.-% at least one additive selected from the group    consisting of defoaming agents, water-repellent agents, surfactants    and coalescing solvents.

More preferably, the binder composition comprises

-   ≥20 wt.-% to ≤40 wt.-% (i) at least one homo- or copolymer of    (meth)acrylic acid,-   ≥20 wt.-% to ≤40 wt.-% (ii) at least one    alkyl(meth)acrylate-styrene-copolymer,-   ≥0.1 wt.-% to ≤5.0 wt.-% (iii) at least one cross-linking agent,-   ≥20 wt.-% to ≤80 wt.-% water and-   ≥1 wt.-% to ≤80 wt.-% at least one additive selected from the group    consisting of defoaming agents, water-repellent agents, surfactants    and coalescing solvents.

Preferably in the binder composition the at least onealkyl(meth)acrylate-styrene-copolymer (ii) is different to the at leastone homo- or copolymer of (meth)acrylic acid (i). In particular the atleast one homo- or copolymers of (meth)acrylic acid (i) is not analkyl(meth)acrylate-styrene-copolymer (ii).

Preferably, the weight ratio of the amount of the at least one homo- orcopolymer of (meth)acrylic acid (i) to the amount of the at least onealkyl(meth)acrylate-styrene-copolymer (ii) is within the range of 1:25to 25:1, more preferably within the range of 1:10 to 10:1, even morepreferably within the range of 1:5 to 5:1 and most preferably within therange of 1:1 to 5:1.

Preferably the at least one homo- or copolymer of (meth)acrylic acid (i)is present in an amount of ≥0.05 to ≤1.0 wt.-%, more preferably in anamount of ≥0.1 to ≤0.8 wt.-%, most preferably in an amount of ≥0.1 to≤0.5 wt.-%, based on the total weight of the briquette.

Preferably the at least one alkyl(meth)acrylate-styrene-copolymer (ii)is present in an amount of ≥0.05 to ≤1.0 wt.-%, more preferably in anamount of ≥0.05 to ≤0.5 wt.-%, most preferably in an amount of ≥0.05 to≤0.3 wt.-%, based on the total weight of the briquette.

Preferably the presently claimed invention is directed to a briquettecomprising

A) ≥99.0 to ≤99.9 wt.-% coal fines and

B) a binder composition comprising

-   -   (i) ≥0.05 to ≤1.0 wt.-% of at least one homo- or copolymer of        (meth)acrylic acid and    -   (ii) ≥0.05 to ≤1.0 wt.-% of at least one        alkyl(meth)acrylate-styrene-copolymer,

whereby each weight is based on the total weight of the briquette.

More preferably the presently claimed invention is directed to abriquette comprising

A) ≥99.0 to ≤99.9 wt.-% coal fines and

B) a binder composition comprising

-   -   (i) ≥0.1 to ≤0.8 wt.-% of at least one homo- or copolymer of        (meth)acrylic acid and    -   (ii) ≥0.05 to ≤0.5 wt.-% of at least one        alkyl(meth)acrylate-styrene-copolymer,

whereby each weight is based on the total weight of the briquette.

Most preferably the presently claimed invention is directed to abriquette comprising

A) ≥99.4 to ≤99.9 wt.-% coal fines and

B) a binder composition comprising

-   -   (i) ≥0.1 to ≤0.5 wt.-% of at least one homo- or copolymer of        (meth)acrylic acid and    -   (ii) ≥0.05 to ≤0.3 wt.-% of at least one        alkyl(meth)acrylate-styrene-copolymer,

whereby each weight is based on the total weight of the briquette.

Preferably in the briquette the at least onealkyl(meth)acrylate-styrene-copolymer (ii) is different to the at leastone homo- or copolymer of (meth)acrylic acid (i). In particular the atleast one homo- or copolymers of (meth)acrylic acid (i) is not analkyl(meth)acrylate-styrene-copolymer (ii).

In the sense of the presently claimed invention, the longitudinaldirection of extension is preferably the maximum extension of thebriquette. The transversal direction of extension is preferably themaximum extension of the briquette orthogonal (perpendicular) to thelongitudinal direction of extension. Typically the longitudinaldirection of extension is longer than the transversal direction ofextension. As the briquette of the presently claimed invention has alongitudinal axis being substantially longer than its transversal axisit exhibits an oblong shape.

In the sense of the presently claimed invention, the length of thebriquette corresponds to the longitudinal direction of extension of thebriquette, the height corresponds to the maximum extension of thebriquette orthogonal to the length and the width corresponds to thetransversal direction of extension orthogonal to the length andorthogonal to the width (Cartesian space).

Preferably the length of the briquette is in the range of ≥1 to ≤10 cm,more preferably in the range of ≥2 to ≤8 cm, most preferably in therange of ≥2 to ≤4 cm. Preferably the height of the briquette is in therange of ≥0.5 to ≤6 cm, more preferably in the range of ≥1 to ≤5 cm,most preferably in the range of ≥1 to ≤2 cm. Preferably the width of thebriquette is in the range of ≥1 to ≤10 cm, more preferably in the rangeof ≥2 to ≤8 cm, most preferably in the range of ≥2 to ≤4 cm.

In another aspect, the presently claimed invention is directed to aprocess for manufacturing a briquette as defined above comprising thesteps of

a) mixing coal fines and a binder composition comprising (i) at leastone homo- or copolymer of (meth)acrylic acid and (ii) at least onealkyl(meth)acrylate-styrene-copolymer to obtain a mixture;

b) forming the mixture obtained according to step a) into a block;

c) drying the block obtained according to step b) to obtain a briquette.

In step a) the coal fines and the binder composition are thoroughlymixed, e.g. in an Eirich mixer, for at least 1 and up to 30 minutes andthen transported, e.g. by using a conveyor belt, to a briquettingapparatus wherein the briquettes are formed. Preferably the coal finesin step a) have a water content in the range of ≥5 wt.-% to ≤20 wt.-%,more preferably in the range of ≥5 wt.-% to ≤15 wt.-%, based on thetotal weight of the coal fines, determined according to standardgravimetric techniques, e.g. determination of water content via ASTMD2216-10.

In step b) the mixture obtained according to step a) is fed to abriquetting apparatus and formed into a block. The briquetting apparatusis preferably a briquetting apparatus that included briquetting rollers.The mixture is fed to the briquetting rollers. The rollers compress themixture.

One or more of the rollers preferably has pockets formed therein whichpockets assist in defining the shape of the briquettes. The rollers alsoapply an amount of shear to the mixture as it passes through thebriquetting apparatus.

In step c) the block is dried for a period of ≥12 to ≤48 h, morepreferably for a period of ≥18 to ≤36 h. The curing temperature ispreferably in the range of ≥10 to ≤45° C., more preferably in the rangeof ≥15 to ≤35° C. Thus, no heating of the briquettes after formation isnecessary as the curing of the briquettes already occurs at roomtemperature.

Preferably in the process of manufacture the at least onealkyl(meth)acrylate-styrene-copolymer (ii) is different to the at leastone homo- or copolymer of (meth)acrylic acid (i). In particular the atleast one homo- or copolymers of (meth)acrylic acid (i) is not analkyl(meth)acrylate-styrene-copolymer (ii).

In another aspect, the presently claimed invention is directed to theuse of a binder combination, as defined above, for the agglomeration ofcoal fines.

In still another aspect, the presently claimed invention is directed tothe use of a binder combination comprising (i) at least one homo- orcopolymer of (meth)acrylic acid, as defined above, and (ii) at least onealkyl(meth)acrylate-styrene-copolymer, as defined above, for theagglomeration of coal fines.

Preferably for the use of the binder composition for the agglomerationof coal fines the at least one alkyl(meth)acrylate-styrene-copolymer(ii) is different to the at least one homo- or copolymer of(meth)acrylic acid (i). In particular the at least one homo- orcopolymers of (meth)acrylic acid (i) is not analkyl(meth)acrylate-styrene-copolymer (ii).

Although the invention has been described with respect to specificembodiments and examples, it should be appreciated that otherembodiments utilizing the concept of the present invention are possiblewithout departing from the scope of the invention. The present inventionis defined by the claimed elements, and any and all modifications,variations, or equivalents that fall within the true spirit and scope ofthe underlying principles.

FIGURE

The FIGURE provided herein represents an example of particularembodiments of the invention and is not intended to limit the scope ofthe invention. The FIGURE is to be considered as providing a furtherdescription of possible and potentially preferred embodiments thatenhance the technical support of one or more non-limiting embodiments.

SHORT DESCRIPTION OF THE FIGURE

FIG. 1 Cumulative % passing as a function of actual size

FIG. 1 describes in particular the cumulative % passing as a function ofactual size with regard to for example coal fines. The size of coalfines according to FIG. 1 is in particular suitable for a briquetteformation in presence of a binder composition comprising at least onehomoor copolymer of (meth)acrylic acid (i), which is not aalkyl(meth)acrylate-styrene-copolymer (ii) and at least onealkyl(meth)acrylate-styrene-copolymer (ii). For example the coal finesaccording to FIG. 1 can be used in a method for manufacturing saidbriquette. In particular the binder composition according to the presentinvention can for example be used for the agglomeration of coal finesaccording to FIG. 1.

EXAMPLE

The invention is further described by the following examples. Theexamples provided herein represent practical support for particularembodiments of the invention and are not intended to limit the scope ofthe invention. The examples are to be considered as providing a furtherdescription of possible and potentially preferred embodiments thatdemonstrate the relevant technical work of one or more non-limitingembodiments.

Coal fines are supplied by a coal mine. The particle size distributionwas determined using Tyler Mesh 16 sieve (1 mm sieve opening). FIG. 1shows the cumulative particle size distribution of the coal fines.

Binder Compositions

Binder composition 1 comprising Acronal@ S728 (available from BASF SE,butyl acrylate-styrene copolymer) and Alcotac® CB 6 (available from BASFSE, copolymer of acrylic acid and acryl amide) in water.

Binder composition 2 comprising Acronal@ S728 (available from BASF SE,butyl acrylate-styrene copolymer) and Alcotac® CB 6 (available from BASFSE, copolymer of acrylic acid and acryl amide) and Reslink® GTC 50(available from Resichem, India, a phenol-formaldehyde resin) in water.

Binder composition 3 comprising polyvinyl alcohol in water.

Binder composition 4 comprising a formulation of butylacrylate styrenecopolymer and a polymer of acrylic acid in water (available as Alcotac®CBF60 from BASF).

Binder composition 5 comprising a formulation of butylacrylate styrenecopolymer and a polymer of acrylic acid in water (available as Alcotac®CBF60 from BASF) combined with a phenol formaldehyde resin (available asAlcotac® CBX60 from BASF).

Formulation of Briquettes

Example 1

The binder composition 1 was mixed with coal fines. The mixture wasthoroughly mixed. The mixture was transferred to a briquetting rollerand briquettes were formed.

Example 2

The process was carried out as described in example 1 except for usingbinder composition 2 instead of binder composition 1.

Comparative Example 3

The process was carried out as described in example 1 except for usingbinder composition 3 instead of binder composition 1.

Example 4

The process was carried out as described in example 1 except for usingbinder composition 4 instead of binder composition 1.

Example 5

The process was carried out as described in example 1 except for usingbinder composition 5 instead of binder composition 1.

The dosage of binder composition in the examples 3, 4 and 5 were asfollows:

Example 3 (comparative): 0.5 wt %

Example 4: 0.07 wt %

Example 5: 0.13 wt %

In Example 5 the binder composition additionally is comprising acrosslinker in a dosage of 0.05% (liquid).

Strength Test

The strength of the briquettes was tested in a drop test. In the droptest the briquette was continuously dropped from a height of 2 metersonto a concrete surface until it completely shatters. The drop test wascarried out to test the green strength of the briquette, whereby thebriquette was in the green state and had undergone no form of curing.Besides the cured strength of the briquettes was tested, whereby thebriquette was allowed to cure at room temperature for a period of 24hours after formation of the briquette.

The strength of the briquettes was tested in a compressive strength. Inthe compression strength test, 20 briquettes were individuallycompressed to break in pieces and data recorded per KgF(kilogram-force). The calculated corresponding SI unit in Newton [N] isgiven in brackets (1 KgF=9.80665 N). The compression test was carriedout to test the green compression strength (Day 0) of the briquette,whereby the briquette was in the green state and had undergone no formof curing. Besides the cured strength (Day 2) of the briquettes wastested, whereby the briquette was allowed to cure at room temperaturefor a period of 48 hours after formation of the briquette.

The strength of the briquettes was tested in a tumbling test. In thetumbling test, 20 briquettes were put in a tumbling drum, rotating at 60rpm for 10 minutes to observe the amount (% of briquettes) of finesgenerated from the briquettes in the tumbling drum. The tumbling testwas carried out on the green briquettes (Day 0) of the briquetteproduction, whereby the briquette were in the green state and hadundergone no form of curing. Besides the cured tumbled briquettes (Day2) of the briquettes were tested, whereby the briquette were allowed tocure at room temperature for a period of 48 hours after formation of thebriquette.

Table 1 reflects the number of drops of the briquette until thebriquette was shattered.

Green strength test Cured strength test Example 1 4 4 Example 2 4 4Comparative 4 4 example 3

The examples 1 and 2 in table 1 demonstrate that the inventively claimedbinder composition leads to the formation of briquettes having astrength that is equal to the strength of briquettes that were formed byusing polyvinyl alcohol (comparative example 3).

Green strength test Cured strength test Example 4 1 3 Example 5 1 5Comparative 1 3 example 3

The examples 4 and 5 in table 2 demonstrate that the inventively claimedbinder composition leads to the formation of briquettes having astrength that is equal to or better than the strength of briquettes thatwere formed by using polyvinyl alcohol (comparative example 3). Inparticular the presence of for example a phenol formaldehyde resin inthe binder composition (example 5) surprisingly shows better resultswith regard to cured strength test in comparison to example 3. Table 3reflects the average compression strength of the briquette in Day 0 forgreen and in Day 2 for cured briquettes.

Green Cured Compression strength Compression strength Example 4 2 KgF (=19.61 N) 4 KgF (= 39.23 N) Example 5 3 KgF (= 29.42 N) 7 KgF (= 68.65 N)Comparative example 3 1 KgF (= 9.81 N) 4 KgF (= 39.23 N)

The results in table 3 for example surprisingly show that the bindercomposition of the present invention in particular with regard toexample 4 and 5 lead to equal or better compression strength (green andcured) in comparison to example 3 where polyvinyl alcohol is used in thebinder composition. In particular the presence of for example a phenolformaldehyde resin in the binder composition (example 5) surprisinglyshows better results with regard to green and cured compression strengthin comparison to example 3.

Table 4 reflects the tumble test strength of the briquette in Day 0 forgreen and in Day 2 for cured briquettes. The lower the amount of finesgenerated, the better the briquettes.

Green Tumble Test Cured Tumble Test Example 4 4.33% 2.71% Example 53.19% 1.36% Comparative example 3 8.33% 2.85%

The results in table 4 for example surprisingly show that the bindercomposition of the present invention in particular with regard toexample 4 and 5 lead to better tumble test strength (green and cured) incomparison to example 3 where polyvinyl alcohol is used in the bindercomposition. In particular the presence of for example a phenolformaldehyde resin in the binder composition (example 5) surprisinglyshows better results with regard to green and cured tumble test incomparison to example 3.

1: A briquette comprising A) coal fines and B) a binder compositioncomprising (i) at least one homo- or copolymer of (meth)acrylic acid and(ii) at least one alkyl(meth)acrylate-styrene-copolymer. 2: Thebriquette according to claim 1, wherein the coal fines comprise at least50 wt.-% coal particles passing Tyler Mesh 16 sieve, 1 mm sieve opening.3: The briquette according to claim 1, wherein the coal fines have anash particle content of up to 40 wt.-% determined according to agravimetric method. 4: The briquette according to claim 1, wherein thebinder composition further comprises at least one cross-linking agent(iii) selected from the group consisting of: a polymer having at leastone functional group selected from the group consisting of hydroxy,primary amine, secondary amine, tertiary amine, epoxy and aldehyde; anda polyvalent metal complex. 5: The briquette according to claim 1,wherein the at least one homo- or copolymer of (meth)acrylic acid (i) isnot an alkyl(meth)acrylate-styrene-copolymer. 6: The briquette accordingto claim 1, wherein the at least one homo- or copolymer of (meth)acrylicacid (i) is selected from the group consisting of: a homopolymer ofacrylic acid, optionally in a form of an alkali metal salt, an alkalinemetal salt, or an ammonium salt; a homopolymer of methacrylic acid,optionally in a form of an alkali metal salt, an alkaline metal salt, oran ammonium salt; a copolymer of acrylic acid, optionally in a form ofan alkali metal salt, an alkaline metal salt, or an ammonium salt, andat least one nonionic monomer; and a copolymer of methacrylic acid,optionally in a form of an alkali metal salt, an alkaline metal salt, oran ammonium salt, and at least one nonionic monomer. 7: The briquetteaccording to claim 1, wherein the at least one homo- or copolymer of(meth)acrylic acid (i) is selected from the group consisting of: ahomopolymer of acrylic acid, optionally in a form of an alkali metalsalts, an alkaline metal salt, or an ammonium salt; a homopolymer ofmethacrylic acid, optionally in a form of an alkali metal salt, analkaline metal salt, or an ammonium salt; a copolymer of acrylic acid,optionally in a form of an alkali metal salt, an alkaline metal salt, oran ammonium salt, and at least one nonionic monomer selected from thegroup consisting of acrylamide, methacrylamide, N-isopropylacrylamide,N-tert-butyl acrylamide, N-methylolacrylamide, methacrylate, ethylacrylate, propyl acrylate and butyl acrylate; and a copolymer ofmethacrylic acid, optionally in a form of an alkali metal salt, analkaline metal salt, or an ammonium salt, and at least one nonionicmonomer selected from the group consisting of acrylamide,methacrylamide, N-isopropylacrylamide, N-tert-butyl acrylamide,N-methylolacrylamide, methacrylate, ethyl acrylate, propyl acrylate andbutyl acrylate. 8: The briquette according to claim 1, wherein the atleast one homo- or copolymer of (meth)acrylic acid (i) has a weightaverage molecular weight of ≥1 000 to ≤5 000 000 g/mol determinedaccording to g gel permeation chromatography measurement. 9: Thebriquette according to claim 1, wherein the at least onealkyl(meth)acrylate-styrene-copolymer (ii) is derived from a mixturecomprising: at least one monomer A selected from the group consisting ofan ester of acrylic acid or methacrylic acid with n-propanol,isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, pentanol,hexanol, 2-ethylhexanol, octanol, decanol, dodecanol and stearyl alcoholand at least one monomer B selected from the group consisting of styreneand-alpha-methyl-styrene. 10: The briquette according to claim 1,wherein the at least one alkyl(meth)acrylate-styrene-copolymer (ii) hasa weight average molecular weight of ≥1 000 to ≤2 000 000 g/moldetermined according to a gel permeation chromatography measurement. 11:The briquette according to claim 1, wherein the at least one homo- orcopolymer of (meth)acrylic acid (i) is present in an amount of ≥0.05 to≤1.0 wt.-% based on the total weight of the briquette. 12: The briquetteaccording to claim 1, wherein the at least onealkyl(meth)acrylate-styrene-copolymer (ii) is present in an amount of≥0.05 to ≤1.0 wt.-% based on the total weight of the briquette. 13: Thebriquette according to claim 1, wherein coal fines are present in anamount of ≥99.0 to ≤99.9 wt.-%, the at least one homo- or copolymer of(meth)acrylic acid (i) is present in an amount of ≥0.05 to ≤1.0 wt.-%and the at least one alkyl(meth)acrylate-styrene-copolymer (ii) ispresent in an amount of ≥0.05 to ≤1.0 wt.-%, each based on the totalweight of the briquette. 14: A process for manufacturing the briquetteof claim 1, comprising: a) mixing coal fines and a binder compositioncomprising (i) at least one homo- or copolymer of (meth)acrylic acid and(ii) at least one alkyl(meth)acrylate-styrene-copolymer to obtain amixture; b) forming the mixture obtained according to step a) into ablock; and c) drying the block obtained according to step b) to obtain abriquette. 15: The process according to claim 14, wherein the coal finesin step a) have a water content in the range of ≥5 wt.-% to ≤20 wt.-%,based on the total weight of the coal fines, determined according to agravimetric method.
 16. (canceled)